This invention relates to a device for holding film in a projector, such as a microfilm printer or enlarger, a microfilm reader, a moving film projector, a composer, or the like.
In FIG. 1 is shown a conventional microfilm printer, comprising a light source box 1 which contains a light source 2, a solenoid 3 for actuating a shutter 4, a condenser lens 5, etc.; a film holding device 6 which includes upper and lower glass clamping members 7 and 8 for clamping a microfilm 9, so that the picture on the emulsified surface of the microfilm 9 is held flat for printing; projecting lenses 10 for focusing the picture onto a photosensitive material; and a printing plate support 11 for supporting a printing plate 12. In this printer the light source box 1, the film holding device 6, and the projecting lenses 10 are movable in the transverse and the longitudinal directions with respect to the printing plate 11, in the same manner as an exposure head in a composer.
When film is held in such a film holding device twisting and distortion of the film are effectively avoided, and the film is well flattened, by arranging the plates 7 and 8 quite close together. However, especially if the device is badly adjusted, there is a risk of scratching the film between the plates 7 and 8, because they clamp it fairly strongly.